Various types of heat exchangers are used in automotive applications. For example, WO03093751, published on Nov. 13, 2003, assigned to Behr, relates to a radiator with an internal fin section, and a short section of tube inside the primary tube. In various evaporator applications, as for example illustrated in WO 2004/005831, evaporators are shown to be provided with a fin that fits against the tube radius for the full length of the tube.
U.S. Pat. No. 5,105,540 issued on Apr. 21, 1992, to Ford Motor Company shows a tube with an internal liner stock for increasing the interior fluid turbulation. U.S. Pat. No. 4,501,321 issued on Feb. 26, 1985, to Blackstone Corporation shows a two piece tube with the overlap occurring at the minor dimension. U.S. Pat. No. 4,813,112, issued on Mar. 21, 1989, to Societe Anonyme des Usines Chausson shows a reinforcement plate on the ambient side of the header to locally reinforce the tube to header joint. U.S. Pat. No. 4,805,693 issued on Feb. 21, 1989, to Modine Manufacturing shows a two piece tube with the overlap occurring at the diameter of the tubing. The above references are incorporated by reference herein.
In recent years, the temperatures and pressures of so-called ‘turbo-charged’ air has significantly increased, resulting in failure of heat exchangers such as those of prior art charge air coolers (CACs), and after coolers due to thermal stresses. In such temperature/pressure conditions, a major disadvantage of prior art designs has been common failures, such as fatigue fracture, of both the tube and the internal fin.
In prior art designs, specific fractures, such as transverse fractures, may occur, for example, at tube locations, and, in particular, at the inlet header of the heat exchangers. Also, internal fin fracture may occur and lead to contamination in heat exchangers such as the charge air in coolers.
Higher temperatures and pressures for CACs are being specified by customers. Even with material changes, increased thickness of materials will be needed to meet these new requirements. Increasing material thickness, which further drives costs. The primary manner in which this has been addressed is through increasing the robustness of the tube through increasing thickness of tube and internal fin. Also, through the adoption of high strength alloys. Although effective in improving durability, these changes require significant tooling, process change, material cost, and overall costs of producing a durable charge air cooler.
There exists a need for a heat exchanger assembly with localized strength which is cost effective and improves durability with increasing pressure/temperature applications.